Printer with rolling anvil member



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PRINTER WITH ROLLING ANVIL MEMBER Filed Aug. 6, 1965 5 SheetsSheet 1 INVENTOR.

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PRINTER WITH ROLLING ANVIL MEMBER Filed Aug. 6, 1965 5 Sheets-Sheet 2 EN TOR.

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PRINTER WITH ROLLING ANVIL MEMBER Filed Aug. 6, 1965 5 She ets-Sheet 5 INVENTOR.

United v States Patent 6 I 3,317,017 PRINTER WITH ROLLING ANVIL MEMBER Charles J. Young, Princeton, NJ., assignor to Radio Corporation of America, a corporation of Delaware Filed Aug. 6, 1965, Ser. No. 477,789 7 Claims. (Cl. 197-1) This invention relates to printers and, in particular, to an improved printer mechanism for use in a serial Printer.

A serial printer is one in which characters are printed seriatim at selected, successive print locations along a document print line. One advantage of a serial printer is that it is relatively simple and inexpensive as compared to a parallel printer or an on-the-fly printer, and requires little or no buffering or memory. An example of a serial printer is the so-called facsimile or matrix printer in which each different character is made up of a distinctive group of small picture elements.

In one known matrix printer, the picture elements of a character are printed column by column from carbon paper by the pressure between seven parallel, independently movable print bars and a scanning anvil. The print bars are located on one side of the document and carbon, and extend across the entire width of the document. These print bars are individually controlled by electromagnets and are movable in a direction generally perpendicular to the surface of the document or paper stock. The anvil is located on the opposite side of the document or paper stock and moves at constant speed from one end of the print line to the other. A character is printed by selective energization of the electromagnets during a series of timed intervals during which the anvil is moved a distance corresponding to the Width of a printed character.

In order to accomplish printing at high speed in such a printer, the print bars should be located as close to the paper as possible, whereby they are required to move only a short distance during printing, preferably a distance of the order of a few thousandths of an inch. A requirement of most printers is that they be able to print multiple copies when the need arises. However, if the number of copies required in a particular application is large, the several documents or sheets of paper and the interleaved carbons may fill the entire space between the print bars and the scanning anvil. In such a situation, there may be sufficient pressure on the carbon to effect undesired printing when no electromagnet is energized. Further, the anvil may drag the paper in the direction of anvil movement. Also, print smearing, dragging and even tearing ofthe paper may result when the anvil moves beneath an actuated printer bar.

Accordingly, it is one object of this invention'to provide an improved printer mechanism.

.It is another object of this invention to provide an improved printer mechanism in which the printer bars may be located very close to the paper without undesired recording when the number of copies is large.

It is a further object of this invention to provide'an improved printer mechanism in which the anvil rolls as it scans along beneath the print bars, whereby there is little or no horizontal drag on the paper.

It is yet another object of the invention to provide an improved anvil assembly.

A printer mechanism embodying the invention comprises a least a first roller which is rolled along a track from one end of the print line' to the other, and a second roller in rolling contact with the first roller and the paper. The second roller functions as a rolling anvil.

In the preferred embodiment, the anvil assembly comprises a carriage which has forward and trailing rollers constrained to move along a track or pair of tracks. The cylindrical scanning anvil is carried by the carriage in rolling contact with the rollers.

3,317,917 Patented May 2, 1967 In the accompanying drawing, like reference characters denote like components, and:

FIGURE 1 is a view in perspective of a printer embodying the invention;

FIGURE 2 is a plan view of the printer;

FIGURE 3 is a fragmentary view taken in the general direction of arrow A of FIGURE 2, and showing details of the printer bar structures and anvil assembly;

FIGURE 4 is an end View of the printer mechanism taken along the lines 44 of FIGURE 2, with the print head mounting bar and plate and the print head casing removed to show the relation of the printer bars to the anvil assembly;

FIGURE 5 is a side view of one of the print head mounting and positioning assemblies;

FIGURE 6 is a view in front elevation of one of the anvil assemblies;

FIGURE 7 is a plan view of the anvil assembly of FIGURE 6; and

FIGURE 8 is a diagram illustrating the method of printing.

The overall printer system will first be described in general terms, after which various portions of the system will be described in detail. Reference should first be had to FIGURES l and 2. As shown therein, the printer system is supported by and between a pair of vertical side plates 12, 14 which, in turn, are mounted 'on, or otherwise supported by, a horizontal base plate It). A platen 16 extends between, and is supported by, the side plates 12, 14 in an elevated position. The top surface of platen 16 lies in a horizontal plane and has a generally oval-shaped raceway 18 therein. Several rolling anvil assemblies 20, three of which are shown in FIGURE 2, move continuously along the raceway. The forward and rear sections of the raceway are straight.

Positioned above platen 16 is a print head which comprises a printer bar housing 24 containing a plurality of elongated printer bar structures. These structures extend from one end of the housing to the other and overlie the forward section of raceway 18. The printer bar structures, which are illustrated in FIGURE 3 and will be described in detail hereinafter, may be seen in FIGURE 1 through the cutout in the front of housing 24. As will be described, the individual printer bar structures are pivotally mounted for movement toward and away from platen 16. At the back right side of the printer bar housing is a solenoid block 26 which houses a plurality of solenoids for individually driving the printer bar structures. Signals are applied to the individual solenoids by way of separate leads in a cable 28.

At the left side of the printer bar housing, as viewed in FIGURE 2, is an end plate 32 to which the housing 24 is atiixed. Plate 32 is pivotally pinned to a lifting bar '34 which is pivotally pinned at its forward end to a stud 36 mounted on side plate 14. The other end of bar 34 overlies a roller 40 carried by and between a pair of vertical side members 42 of a supporting yoke. A similar lifting bar assembly is located at the right side of the printer bar housing and comprises a lifting bar 50 pivotally pinned at its forward end to a stud 52 mounted on side plate 12. The back end of lifting bar 50 overlies a roller 54 carried by and between a pair of vertical side members 56 of a supporting yoke. Bar 50 is pivotally pinned to an end plate 58 afiixed at the right end of the printer bar housing 24. As illustrated in FIGURE 2, end plate 58 may also serve as a support for the solenoid block 26. The supporting yokes are fixedly mounted on -a cam shaft 62, which is rotatable in bearings (not shown) in side walls 12 and 14. The right hand end of the shaft projects through an aperture in side plate 12 and is coupled to the shaft 64 of a rotary solenoid 66.

Documents to be printed are movable along'a feed path between the top of platen 16 and the bottom of printer bar housing 24. Thus, the printer bar structures comprising the print head are located above the document, or document receiving zone at the print station, and the anvil assemblies 20 move beneath the document, or document receiving zone. The anvil assemblies are so spaced from one another that only one anvil assembly moves beneath the printer bars at any one time. The document may be one having a carbon backing. Alternatively, a separate sheet of carbon may be provided for each document at the print station.

The printer system is designed to handle documents in the form of continuous sheets of paper stock and carbon supplied from rolls or from fanfold stacks (not shown). A section of paper stock is illustrated in phantom in the drawing and may be identified by reference character 72. Multiple copies may be printed simultaneously by feeding a sheaf of interleaved carbons and paper stock through the print station from different supply rolls. The paper stock and carbons are of the type which have sprocket feed holes near both side edges.

Located at the front of the printer is a pair of paper feed tractor assemblies 76, 78. A like pair of tractor assemblies 80, 82 is located at the rear of the printer. These assemblies are alike in construction, wherefore only assembly 78 will be described in any detail. This assembly is mounted on a fixed supporting rod 84 and includes (FIGURE 1) an endless chain 86 mounted on a pair of spaced wheels 88 and 90. Wheel 88 is an idler wheel which is part of the tractor assembly proper. Wheel 98 is a drive wheel which is mounted on a tractor shaft 92. Shaft 92 extends through apertures in the side walls 12, 14 and is rotatable in bearings therein.

Each of the links in chain 86 has a projecting tab 96 which carries an upstanding sprocket tooth 98. Both the chain 86 and the sprocket teeth 98 lie in planes which are parallel to the side walls 12 and 14. A horizontal platform 100 for supporting the paper is fixedly attached to the assembly. The sheaf of paper stock and carbons rests on platform 100 with the top sprocket teeth 98 projecting upwards through the sprocket holes in the sheaf. A retaining member 102 is hinged on the tractor assembly and is adapted to clamp down loosely on the top of the sheaf to assure that the sprocket holes in the sheaf of papers are maintained in cooperation with the sprocket teeth 98. The retaining member 102 is shown in an upright position in FIGURE 1 for receiving a new document. After the document is properly positioned on the tractor assemblies 76, 78, 80 and 82, the various retaining members are moved to the horizontal or paper retaining position (see assembly 76, for example) and held in that position by bias springs 104. Retaining member 102 has an elongated slot 108 through which the top sprocket teeth 98 project when the retaining member is in the horizontal position.

All of the tractor assemblies are movable. Ordinarily, of course, tractor assembly 78 is clamped in a fixed position on rod 84, and drive wheel 90 is clamped to tractor shaft 92. However this entire assembly may be unclamped and slid along rod 84 and shaft 92. The other tractors are similarly movable. Thus, paper stock of various widths can be accommodated.

A first bevel gear 110 is fixedly mounted on the left end of tractor shaft 92. Cooperating therewith, and driven thereby when tractor shaft 92 rotates, is a second bevel gear 112 mounted on the forward end of a pinion shaft 114. The latter shaft is supported near its forward end in a bearing housing 116 mounted on the left end of rod 84, and is supported near its back end in a bearing housing 118 (FIGURE 2) on the left end of fixed rod 120. A third bevel gear 122 is mounted on the back end of pinion shaft 114 and drives a fourth bevel gear 124. Fourth bevel gear 124 drives the back tractor shaft 132 by Way of a spur gear differential housed in box 128. A first sun gear (not shown) of the differential is pinned to fourth bevel gear 124 and driven thereby. The second sun gear of the differential is mounted on the end of back tractor shaft 132. Thespider containing the sun gears is spring biased by a spring 134 connected to a pin 136, and spring 134 biases the spider in a direction to maintain the paper flat and under tension in the area between the front and back tractor assemblies.

During the printing of a line of information, the tractor shafts 92 and 132 are stationary. For reasons to be discussed later, the sheaf of documents and carbons is pressed down firmly against the platen 16 at this time and held in clamped position by the housing 24. In order to advance the paper when printing of a line thereon is complete, it is first necessary to raise the print head away from the platen. The manner in which this is accomplished may best be seen from a consideration of FIGURES 2 and 5, of which the latter is a side view of the right hand lifting bar arrangement. The yoke and side members 56 thereof are shown therein in the normal or rest position (rotary solenoid 66 de-energized). Lifting bar 50 has its right end overlying the roller 54 carried between the side members 56.

To lift the printer bar housing, a signal is applied over cable 70 (FIGURE 2) to energize the rotary solenoid 66. When the solenoid is energized, cam shaft 62 is rotated through a given angle in the direction indicated in FIGURE 5, and rotates the yoke through the same angle. When the yoke is rotated, the roller 54 rides along the chamfered cam surface of lifting bar 50 and causes the bar to rotate in an upward direction about the pivot pin in the stud 52. The end plate 58, and the printer bar housing 24 affixed thereto, are thus moved in an upward direction away from the paper stock. The action of the left hand lifting bar 34 assembly is similar to that just described. Since end plate 58 is coupled to bar 50 by a pivot pin 60, the plate 58, print head, etc. will tend to rotate about pin 60, during the upward movement of the bar, due to the weight of the solenoid block 26. To limit the amount of rotation, a pin 61 is mounted on plate 58 and extends through an oversized aperture 63 in bar 50.

Paper advance is controlled by a rotary solenoid 150, which receives an energizing signal over line 152. The shaft 154 of the solenoid rotates through a given angle when the solenoid is energized and, in turn, rotates a link 156 through the given angle. Pinned at the end of link 156 is an arm 158 which is coupled at its forward end to tractor shaft 92. Coupling may be made by way of a cam clutch 160 or other clutch arrangement of a type wherein the clutch grips the tractor shaft instantaneously when the arm 158 is rotated in a first direct-ion by the energized solenoid, and wherein the clutch is freely rotatable in the opposite direction. In particular, when solenoid 150 becomes energized, the back end of arm 158 is driven in a downward direct-ion by link 156 and, in turn, rotates tractor shaft 92 a given amount in the direction indicated in FIGURE 1. Back tractor shaft is rotated in the same direction through the gear train described prevlously. When solenoid becomes deenergized, the back end of arm 158 is driven in an upward direction by link 156 to the rest position. However, arm 158 does not rotate shaft '92 during its upward movement because of the action of the clutch 160. In order to prevent movement of the paper in the opposite direction, a ratghet wheel 164 is mounted on the right end of tractor shaft 92. A pawl arm 166 is biased into engagement with the ratchet wheel and prevents rotation of the latter in a counterclockwise direction, as viewed from the right side of the printer. The paper 72 also may be moved manually any given amount by turning the hand knob 168 on the end of tractor shaft 92.

The printer bar structures and their relation to other components at the print station are shown in detail in FIGURES 3 and 4. Consider the forwardmost printer bar structure in FIGURE 3 by way of example. This structure 198 comprises first and second elongated members 200, 202 which extend from one end of the printer bar housing 24 (FIGURES 1 and 2) to the other across the width of the paper stock. A plurality of struts 204a204n are arranged in a regular or repetitive zigzag pattern along the lengths of the elongated members 200, 202, and are joined at their opposite ends to the bottom of member 200 and the top of member 202. These struts 204a-204n maintain the elongated members 200, .202 in spaced, parallel relation, whereby the structure 198 may be made very thin and light in weight while still retaining structural stability. This is very desirable in the interests of providing a low inertia structure for high speed printing.

The various printer bar structures, seven of which are shown, are stacked in side-by-side relation one behind the other (FIGURE 4), and are held in stacked relation by the front and back sections 24a and 24b of the printer bar housing. This prevents the light weight structures from wobbling or twisting as they move. Front housing section 24a has a pair of elongated bumper ribs 210 which extend the length of the housing, and back housing section 24b has a pair of similar, opposed bumper ribs 212. The ribs 210 and 212, which are in contact with the struts of the first and last printer bar structures, re-v spectively, provide support for the stack while at the same time presenting a relatively small surface area of frictional contact with the struts of the associated structures.

The ends of all of the printer bar structures are aligned. As may be seen in FIGURE 3, the zigzag pattern of struts of adjacent printer bar structures are outof-phase with each other by approximately a quarter of a pitc or a quarter of a pattern section. By this arrangement, the struts of one printer bar structure are transverse to adjacent struts of next adjacent printer bar structures, whereby there is only a small area of frictional contact between struts of adjacent structures; The aforementioned and other features of the printer bar structures are discussed in greater detail in the copending application of Maurice Artzt, Ser. No. 477,875, entitled, Printer, which is filed concurrently herewith and assigned to the same assignee as the instant invention.

Each of the printer bar structures is pivotally mounted for rotation toward and away from the platen 16. Forwardmost structure 198 has a vertically projecting tab 220 at the top right end thereof. A pivot pin 222 extends through an aperture in the tab 220 and is aflixed at its other end to a crank arm 223, which is fastened to the shaft 225 of the armature 224 of a first solenoid 226. Armature 224 rotates shaft 225 when solenoid 226 is energized. Although it is not clearly shown in FIGURE 4, the left end of shaft 225 may be supported in a hearing in the rear housing section 2412, and the right end of the shaft may be supported in a bearing in the back wall of the solenoid housing block 26 (FIGURE 1). Structure 198 also has one or more other vertically projecting tabs spaced along the length of the member 200. One of these latter tabs 228 is illustrated in FIG- URE 3 and is pivotally pinned to a link 230 which, in turn, is pivotally mounted on a fixed pin 232. Thus, the entire printer bar structure 198 can swing through a small angle on shaft 225 and pivot pin 232.

Elongated members 200 and 202 are parallel to one another. A-lso, the shaft 225 and pin 232 lie in a horizontal plane, and the distance between pin 222 and shaft 225 is the same as that between pins 232 and 234. Accordingly, the entire bottom surface of elongated member 202, which is the printing surface, is always in a horizontal plane and parallel to the paper, regardless of the position of the printer bar structure 198. Each of the other printer bar structures is similarly mounted. Tab 238 at the right end of the second printer bar structure, for example, is pivotally mounted on a pin 240 which is afiixed at its back end to a crank arm 241 fixed to the shaft of the armature 242 of solenoid 244.

In operation, the bottom, printing surfaces of all of the printer bar structures rest in contact with the top sheet of paper (or carbon) when the solenoids are deenergized. In prior art arrangements which employ a plurality of elongated printer bar structures, the anvil which is scanned or moved beneath the printer bars, from one end thereof to the other, is of a type which is rigidly mounted on a drive belt or other transport means. Accordingly, the anvil translates as it scans beneath the printer bars. Printing is accomplished by driving one or more of the printer bars in a downward direction to press the documents and carbons against the scanning anvil. In the arrangement of FIGURE 3, for example, the printer bars are selectively driven in a downward direction by energizing the associated solenoids. When solenoid 226 is energized, the top of armature 224 is attracted to the core 250 of the solenoid, whereby the armature 224 rotates shaft 225 in a counterclockwise direction and drives the printer bar 198 against the anvil.

Inorder to provide uniform print density throughout a document and readable print on all of the copies, it is generally necessary to press the sheaf of papers firmly against the scanning anvil during printing. When the anvil is of the prior art type which only translates, the anvil may drag the paper or papers in the direction of an'vil movement due to friction resulting from the pressure imposed by the activated printer bars. In fact, the paper may even tear. Further, if the printer bars are in contact with the paper when no solenoid is energized and the anvil also is in contact with the paper, undesired printing and smearing may result, even though no printmg is desired. These objectionable features of prior art systems are eliminated by the novel rolling anvil pin assembly of my invention.

In general terms, the rolling anvil assembly of my invention comprises at least one roller which is rolled along a track on one side of the paper from one end of the print line to the other. A cylindrical anvil pin, having its axis parallel to that of the roller, is disposed between the roller and the paper, and is maintained in rolllng contact with the roller as the latter rolls along the track. Preferably, the anvil pin also is in rolling contact with the paper as the pin scans along the print line. Regardless of the printing pressure, there is rolling friction only between the anvil pin and the document, whereby there is no tendency for the anvil pin to drag the paper. Also there is rolling friction only between the anvil pin and the roller, and between the roller and the track.

The particular manner in which the desired physical relationship between the anvil pin and roller is maintained, and hence the actual form the assembly may take, depends upon the drive means employed, the available space, and other factors. A preferred form of anvil assembly embodying my invention is shown in enlarged side view in FIGURE 6 and in plan view in FIGURE 7. As there illustrated, the assembly includes a carriage body 270 borne by a pair of rollers whose axes are parallel to one another. Each of the rollers preferably comprises a pair of wheels mounted on a common axle. For example, the first roller may comprise a pair of wheels 272, 274 mountedon an axle 276 which projects through the front and back side walls of the carriage body 270. The central portion 280 of the axle may be larger in diameter than that portion of the axle on which the wheels 272 and 274 are mounted. The second roller preferably comprises a pair of wheels 284, 286 mounted on an axle 288 which projects through the front and back side walls of the carriage body 27 0. Each of the wheels 272, 274, 284 and 288 has a radius R The front side wall of the carriage body, which wall is transverse to the axles 276, 288, has a rounded notch 292 in the top edge thereof. The radius of this notch is R and the center of the notch is equidistant from the axes of rotation of all of the wheels, and spaced therefrom a distance less than R +R Thus, as may be clearly seen FIGURE 6, the portions of the notch nearest the wheels 272 and 284 are closer than R to the axes of rotation of the wheels. A similar notch is located in the back side wall of the carriage body 270 and has its center aligned with the center of notch 292 parallel to the axles 276 and 288.

A cylindrical anvil pin 2% is cradled in the notches in the two side walls and projects outward from the carriage body in either direction. The radius of the anvil is slightly less than that of the notches, whereby the anvil is free to rotate. Moreover, the centers of the notches are below the top edges of the side walls, whereby the openings at the tops of the notches are less than the diameter of the anvil pin and the anvil pin 296 cannot escape from the notches at the tops thereof. The carriage body 270 also has a top member 294 which extends between the front and back walls and terminates adjacent the notches in the side walls. The carriage body 270, although not essential to the invention, provides a convenient means for assuring the proper physical relationship between the anvil pin 296 and the wheels, as well as a convenient means for driving the wheels.

A vertical pin 298 projects downward through the bottom of the carriage body, and may be attached to drive means to be described. Because of the particular relationship of the radii of the 'wheels 272, 274, 284, 288, the notches and the anvil pin 296, the anvil pin 2% is in contact with all of the wheels. When the assembly is driven, the wheels roll along the supporting surface (to be described), and the anvil pin 296 preferably rolls along the bottom surface of the sheaf of documents. The Surface speeds of the anvil pin and the wheels are equal to each other and to the speed of the carriage. Moreover, the direction of rotation of the anvil pin is opposite to that of the 'wheels. Hence, there is rolling friction only, both at the surface of the sheaf of documents and at the surface of the raceway, regardless of the pressure of the printer bar structures on the anvil pin 2%. There is thus no tendency for the anvil pin to drag the paper in the direction of movement of the carriage. Further, the rolling action of the anvil pin eliminates, or at least greatly reduces, print smearing and undersirable printing when the printer solenoids are deenergized.

The anvil assemblies are driven continuously around the raceway 18 (FIGURE 2) and beneath the printer bar structures. As may be seen in FIGURES 3 and 4, the platen 16 preferably comprises two plates 16a, 161) which are sandwiched together. The raceway 18 (FIGURE 2) is located in upper plate 161) and comprises a groove or channel which is rectangular in cross section and has a slot at the bottom thereof. The vertical carriage pin 298 projects through this slot, and the carriage wheels ride along the bottom of the groove on either side of the slot. Essentially, the bottom surfaces 310, 312 of the groove serve as tracks for the carriage wheels. The width of the channel is only slightly greater than the length of the anvil pin, whereby the pin cannot escape from the carriage at the sides thereof.

The bottom plate 16a of the platen is hollow in the area beneath the entire raceway. Located in this hollow, near one end of the raceway, is a drive sprocket wheel 320, shown in FIGURE 4. A second, idler sprocket wheel is located in the hollow at the other end of the raceway, and a chain 322 is carried by the drive wheel 320 and the idler wheel. Drive wheel 320 has teeth 324 which are spaced to mesh with the links of the chain. Drive wheel 320 is driven by a motor (not shown) at constant speed and, in turn, drives the chain at constant speed below the raceway. The pins 298 of the different carriage assemblies are affixed to different ones of the links, whereby they are driven by the chain at constant speed. As clearly shown in FIGURES 3 and 4, the top longitudinal surface of that anvil pin which is moving beneath the printer bar structures faces the bottom, printing surfaces of the structures, and is closely adjacent to the bottom of the sheaf of papers.

Preferably, the top surface of the anvil pin 2% is in contact with the bottom paper. The printer bar structures are so suspended (FIGURE 3) that they are free to pivot under their own weight intolight contact with the top of the paper. However, because of the light weight construction of the structures and the rolling action of the anvil pin, there is insufiicient pressure therebetween to cause printing or smearing when no printer solenoid is energized. An advantage of this spatial relationship between the rest positions of the printer bar structures and the rolling scanning anvil pin is that the structures need only move a very short distance to effect printing. For example, a printer bar structure may move about 0.003 inch when its solenoid is energized.

A further advantage of the spatial relationship is that the activated printer bar structures move approximately the same distance regardless of the number of copies in the sheaf. Thus, there is no need to make printer adjustments when the number of copies is changed. This assumes, of course, that there are no substantial air pockets between the various carbons and papers. To assure this condition, and to reduce the driving force required of the printer solenoids, the bottoms of the front and back sections 24a and 24b of the printer bar housing are provided with spaced legs 340 and 342 (FIGURE 4) which extend the length of the housing. These legs are flat on the bottom faces thereof, and are separated a distance somewhat greater than the length of the anvil pin 296. In the normal, rest position of the housing 24, the housing 24 is biased or pressed firmly in a downward direction by a low rate spring 63 (FIGURE 5). The legs 340, 342 press against the sheaf of documents and carbons and squeeze out any air therebetween in the area of the print station. Further details of the printer bar housing 24 construction, and the lifting bar arrangement for the housing, are given in the copending application of Everett I. West, Ser. No. 477,871, entitled, Printer, which is filed concurrently herewith and assigned to the same assignee as the present invention.

Printing is effected by energizing selected ones of the printer solenoids as an anvil pin 296 scans along the path beneath the printer bar structures. A character is printed at a desired location in the print line in a series of columnwise steps as the anvil pin is moved a distance equal to a character width at the desired location. The motion of the anvil may be considered to be divided into seven time zones per character. Five zones are used for printing, and two zones are allotted to intercharacter spacing. During each printing time zone, one or more of the printer solenoids may be energized to drive its associated printer bar structure in a generally downward direction to press the carbon and paper against the scanning anvil.

FIGURE 8 illustrates the manner in which a capital E is printed. All of the solenoids are energized during the first time zone to print a column of seven marks or picture elements. Only the solenoids for the first, middle and last printer bar structures remain energized during the second, third and fourth time zones, and the solenoids for the first and last printer bar structures remain energized during the fifth time Zone.

Although the invention has been described and illustrated as being embodied in a multi-printer bar printer system for printing characters in a 5 x 7 font, it will be understood by those skilled in the art that the invention has equal application in a single printer bar system for facsimile printing.

What is claimed is:

1. In a printer, the combination of:

a document path;

a print head disposed on one side of said path;

a track disposed opposite the print head and parallel thereto on the other side of the document path;

at least a first, drive roller;

means for rolling said drive roller on said track;

a cylindrical anvil pin adjacent the document path and in printing relation to said print head; and

means maintaining said anvil pin in rolling contact with said drive roller for rotation thereby as said drive roller is rolled on said track.

2. A rolling anvil assembly for a printer comprising:

a pair of rollers of radius R having their axes in parallel, and a carriage body borne by said rollers;

said body including first and second spaced side members transverse to said axes;

a first rounded notch of radius R in the top edge of the first side member, the center of said first notch being located at a distance greater than R from said top edge and being located at a distance less than R +R from the axis of at least one of said rollers;

a second rounded notch, similar to said first notch, in the top edge of the second side member, the centers of the first and second notches being aligned parallel to the axes of said rollers; and

a cylindrical anvil cradled in said notches and having a radius less than R whereby said anvil is in frictional contact with said one of said rollers and is free to rotate in said notches.

3. The combination as claimed in claim 2, wherein each of said rollers includes a pair of wheels of radius R; and an axle on which said wheels are mounted.

4, In a recorder for recording information on a recording medium, the combination of:

a path for receiving a recording medium;

a recording head located on one side of said path;

a pair of drive rollers located on the other side of said path;

means maintaining said rollers in fixed spatial relation to one another with their axes in parallel;

means for rolling said rollers in a direction from one end of said recording head to the other;

a rotatable, cylindrical anvil adjacent said path and in recording relation to said recording head; and means maintaining said anvil in frictional contact with at least one of said rollers for rotation thereby as the latter is rolled.

5. In a printer for printing information on a document, the combination of:

a document receiving path;

a plurality of printer elements located on one side of said path and defining a print head;

means for moving said printer elements selectively toward said document path;

a carriage on the other side of said document path and including a pair of rollers and a carriage body borne by said rollers;

a cylindrical anvil pin in frictional contact with at least one of said rollers and supported for rotation thereby in said carriage body, the axis of said anvil pin being parallel to the axes of said rollers; and

means for driving rollers in a direction from one end of said print head to the other, with a surface of said anvil pin being adjacent to said document path and in printing relation to said printer elements.

6. In a printer for printing a line of information on a document, the combination comprising:

a document path;

at least one elongated printer bar disposed on one side of said document path and having a printing surface facing said path;

a carriage oppositely disposed to said printer bar on the other side of said path and including two sets of wheels having their axes in parallel and a carriage body borne by said wheels;

a cylindrical anvil pin in frictional contact with each of said wheels and supported for rotation thereby in said carriage body, with a longitudinal surface of said anvil pin projecting above the top of said carriage body; and

means for driving said carriage from one end of said printer bar to the other with the top of said carriage body facing the printing surface of said printer bar and with the anvil pin adjacent to said document path and in printing relation to said printer bar.

7. In a printer for printing a line of information on a document, the combination comprising:

a document path;

a plurality of elongated printer bars disposed in sideby-side relationship on one side of said path and each having a printing surface facing said path;

a carriage assembly oppositely disposed to said printer bars on the other side of said path and including a pair of rollers of radius R having their axes in parallel, and a carriage body borne by said rollers and having first and second spaced side walls transverse to said axes;

a first rounded notch of radius R and depth D in the top edge of the first side wall, where R D 2R and a similar, second rounded notch of radius R in the top edge of the second side wall, the centers of said notches being aligned parallel to said axes and being equidistant therefrom at a distance less than 1+ 2;

a cylindrical anvil cradled in said notches and having a radius less than R and means for driving said carriage assembly on said rollers from one end of said print-er bars to the other with a longitudinal surface of said anvil facing said printing surfaces and being adjacent to said document path and in printing relation to said printer.

References Cited by the Examiner UNITED STATES PATENTS 1,271,687 7/1918 Evans 101-51 1,393,827 10/ 1931 Raymond 10151 2,058,511 10/1936 Rutkoskie 101-302 X 2,181,714 11/1939 Vandercook et al. 101-354 2,656,240 10/1953 Hell 1971 X 2,659,652 11/1953 Thompson 10193 2,790,697 4/ 1957 Wockenfuss 197-1 X 2,909,996 10/ 1959 Fitch 10193 2,976,801 3/1961 Dirks 101-93 3,155,032 11/ 1964 Antonucci 10193 3,157,456 11/1964 Kikuchi 34678 3,164,083 1/ 1965 Irvine 10193 3,223,029 12/ 1965 Simshauser 34678 X ROBERT E. PULFREY, Primary Examiner.

E. S. BURR, Assistant Examiner. 

1. IN A PRINTER, THE COMBINATION OF: A DOCUMENT PATH; A PRINT HEAD DISPOSED ON ONE SIDE OF SAID PATH; A TRACK DISPOSED OPPOSITE THE PRINT HEAD AND PARALLEL THERETO ON THE OTHER SIDE OF THE DOCUMENT PATH; AT LEAST A FIRST, DRIVE ROLLER; MEANS FOR ROLLING SAID DRIVER ROLLER ON SAID TRACK; A CYLINDRICAL ANVIL PIN ADJACENT THE DOCUMENT PATH AND IN PRINTING RELATION TO SAID PRINT HEAD; AND MEANS MAINTAINING SAID ANVIL PIN IN ROLLING CONTACT WITH SAID DRIVE ROLLER FOR ROTATION THEREBY AS SAID DRIVE ROLLER IS ROLLED ON SAID TRACK. 